Anode for cathodic protecting systems



Jan. 12, 1954 w, VALLETT 2,666,027

ANODEI FOR CATHODIC PROTECTING SYSTEMS Filed Jan. 13. 1949 INVENTOR. mumI. VMLETT QwZ/KQZMW A TTOALA/EY Patented Jan. 12, 1954 ANODE FORCATHODIO. PROTECTING SYSTEMS Walter I. Vallett, Detroit, Mi'ch.,assignor to The Corrosion Control Company, Midland, Mich, a. company ofMichigan Application January 13, 1949, Serial No. 70,670

3 Claims. l

The invention relates to the electrolytic protection of metallicsurfaces against corrosion, and more particularly relates to an improvedelectrode construction for use in an electrolytic system adapted toprotect metal surfaces in containers, such as water heaters, condensers,heat exchangers and the like.

It is now an established practice in the art to which the inventionrelates to protect the common structural metals such as iron, steel,galvanized iron, and the like by the use of a metallic anode having asolution potential greater than that of the metal to be protected. Ithas been found that, in the main, corrosion of these containers iselectrolytic in nature and is associated with the flow ,of electriccurrents between various parts of the metal surfaces. By the properutilization of a metallic anode having a higher solution potential thanthe metal to be protected a controlled electric current is pro videdwhich renders thestructural metal cathodic and thus without tendency togo into solution due to electrolytic action, while producingelectrolytic corrosion of the anode with its attendant solution.

For example, in the case of the household hot water heaters, itis nowcustomary to insert a magnesium rod into the tank to be protected insuch a manner that the magnesium anode contacts the fluid in the tankand at the same time is in electrical contact with the structural metalof the tank. This electric cell formed operates by the magnesium anodeslowlygoing into solution in: the electrolyte while the tank acting asthe cathode is protected to the extent that it I exhibits no tendency tocorrode or go into solution due to the action of the water.

In those instances where the magnesium anode is included in the assemblyprior to installation no difficulties are encountered since a continuousrod of magnesium can be inserted readily and properly connected to oneofthe usual nipples provided for the water connections. However in thoseinstances where a tank, such as a hot water heater, has already beeninstalled or renewal of the anode is indicated it oftentimes happensthat the clearances are such that a continuous section anode can not beinserted or otherwise installed in the tank. To overcome this difficultyit has been proposed to make the anode in short sections or segmentswith a soft iron wire core acting to hold the sections together as acontinuous or single anode. In practice it has been observed that theanode sections often become separated from each other due to breakage ofthe iron wire core between the sections as the anodes assembly is flexedin packaging and during the assembly operation. This difficulty is alsofrequently encountered when a braided or woven iron or copper core issubstituted for the usual iron wire core.

The present invention resides in the discovery that by using a springconnector between the anode sections, and preferably a coil springconnector, this difficulty is entirely eliminated and the electrodeassembly can be doubled up into a compact unit for shipping and yet bereadily inserted into a tank where minimum clearances obtain without theattendant danger of the electrode sections becoming separated fromeachother.

It is therefore the principal object of the in-- vention to provide asectionalized electrode structure wherein the various sections areconnected together by a spring.

Another object of the invention is to provide a'sectionalized magnesiumanode structure hav ing a metal core wherein the various sections are inelectrical connection by means of a spring.

A further object of the invention is to provide a magnesium anodeassembly in which sections of magnesium are formed over a dissimilarmetal core and connected together by means of a coil spring.

Other further objects and advantages will be apparent during the courseof the following description which taken in conjunction with the annexeddrawing illustrates a way of putting the invention. into effect, suchdisclosure illustrating but one of various ways in which the principleof the invention may be used.

In the drawing:

Fig.1 is a side elevation partly in section illustrating the newelectrode structure installed in a conventional hot watertank.

Fig. 2 is a. sectional view in enlarged detail showing two ,sections ofthe anode connected together in the preferred manner of the invention.

Fig. 3 is an enlarged sectional view of two anode sections connectedtogether by a spring member.

Fig. 4 is an enlarged sectional view showing another embodiment of theinvention.

Referring to Fig. 1, hot water tank 5 is provided at the top with theusual threaded holes into which nipples 2 and 3 are screwed. Nipple itforms a portion of the anode assembly in that a wire or bar 4 issoldered or otherwise electrically connected to the nipple. The wire 4is atr 3 tached to one end of a spring member 5 while the other end ofspring 5 is soldered or otherwise electrically connected to the wirecore'G (see Fig. 2) extending through the anode segment or section '3.Each additional section or segment of the anode assembly is similarlyconnected to a spring 5 in a like manner.

In the enlarged detail of the spring and sectionalized anode shown inFig. 2 adjacent anode sections 1' with the wire cores 6 are shownconnected together by a coaxially disposed coil spring 5 interposedtherebetween. Coil spring 5 is preferably tapered at either end at 8 soas to accommodate the core wire or rod 6. The cores 6 are held to thespring 5 as by soldering which may fill the tapered ends thereof, asindicated at 9, sole mechanical and electrical connection between theanode sections.

In the embodiment of the invention shown in 3 anode sections W withcores H are connected together by fiat bar spring members l2. The barspring 12 is forged at either end into a sleeve portion'lit toaccommodate the metal core members ii. By filling the sleeve 13 withsolder is or the like a strong connection is obtained.

In the embodiment illustrated in Fig. 4 the metal core has beendispensed with and the end of the magnesium anode segment 85 is undercutat E5 and threaded to engage a metal cap I! of a dissimilar metal suchas brass, bronze, or iron. The metal cap i? is provided with a centrallydisposed and outwardly extending lug 58 which provides a means forconnecting to spring H as by soldering at 20. It will be apprehendedthat each end of the intermediate segments of the assembly will beprovided with a cap and connected to the adjoining segment. The last orlower segment will of course need no cap on one end. At the upper end ofthe electrode assembly illustrated by Fig. 4 the lug will be connectedto the tank in the manner described in connection with Fig. 1.

It will be readily understood that the wire core and properly spacedsprings may be formed from a single piece of wire it being onlynecessary to cast the magnesium segments over the wire core at theproper location.

In the foregoing manner a sectionalized anode is provided which ispermanently flexible so that it may be compactly boxed for shipping andcan be flexed readily and easily during installation without danger offailure.

While the invention has been described particularly with reference toanodes for use in connection with hot water heaters it is to beunderstood that the construction described is applicable for use incontainers such as condensers, heat exchangers, and the like whereinstallationlimitations require the use of a flexible sectionalizedelectrode. Additionally it will be apparent that while the invention hasbeen described with particular reference to magnesium anodes becausemagnesium possesses unusually desirable solution potential properties itis equalwhereby'the spring provides the ly adaptable for use withaluminumyzinc and similar metal electrodes possessing a higher solutionpotential than the metal to be protected. The term magnesium as usedherein and in the appended claims is intended to include the pure metalas produced commercially as well as the many alloys thereof.

I claim:

1. An anode assembly for the electrolytic protection of a metalcontainer comprising a plurality of anode segments of a metal having ahigher solution potential than the container to be protected,coil-spring connectors interposed between and in axial alignment withthe segments and providing the sole mechanical and electricalinterconnection therebetween, and means at one end of the segmentedanode assembly for connecting same to the container.

2. An anode assembly for the electrolytic protection of a metalcontainer comprising a plurality of anode segments of a metal having ahigher solution potential than the container to be protected, and eachincluding a core extending axially therethrough of a metal having alower solution potential than said container, coil-spring connectorsinterposed between and in axial alignment with the segments, saidconnectors being mechanically and electricallyconnected to the segmentcores and providing the sole connection between the segments, and meansat one end of'the segmented anode assembly for connecting same to thecontainer.

3. An anode assembly for the electrolytic protection of a metalcontainer comprising a plurality of anode segments of a metal having ahigher solution potential than the container to be protected, and eachincluding end caps affixed to the ends of the segments of a metal havinglower solution potential than said container, coil-spring connectorsinterposed between and in axial alignment with the segments and beingmechanically and electrically connected to the adjacent end capsthereof, and providing the sole connection between the segments, andmeans at one end of the segmented electrode assembly for connecting sameto the container.

WALTER I. VALLETT.

References Cited in the file or this patent UNITED STATES PATENTS NumberName Date 114,191 Parmelee Apr. 25, 1871 642,873 Palmer Feb. 6, 1900752,844 Kinnear Feb. 23, 1904 1,489,743 Delius et a1 Apr. 8, 19242,451,064 Butler Oct. 12, 1948 2,459,123 Bates et al. Jan. 11, 19492,508,171 Kaufman May 16, 1950 FOREIGN PATENTS Number Country Date20,655 Great Britain of 1894

1. AN ANODE ASSEMBLY FOR THE ELECTROLYTIC PROTECTION OF A METALCONTAINER COMPRISING A PLURALITY OF ANODE SEGMENTS OF A METAL HAVING AHIGHER SOLUTION POTENTIAL THAN THE CONTAINER TO BE PROTECTED,COIL-SPRING CONNECTORS INTERPOSED BETWEEN AND IN AXIAL ALIGNMENT WITHTHE SEGMENTS AND PROVIDING THE SOLE MECHANICAL AND ELECTRICALINTERCONNECTION THEREBETWEEN, AND MEANS AT ONE END OF THE SEGMENTEDANODE ASSEMBLY FOR CONNECTING SAME TO THE CONTAINER.